Alkaloid variation in the Lupinus pusillus group (Fabaceae: tribe Genisteae)

The major alkaloids of Lupinus pusillus and related species were studied by GC and GC-MS. More than 25 alkaloids were detected in 20 extracts from L. flavoculatus, L. kingii, L. odoratus, L. pusillus and L. shockleyi. Esters of alkaloids appear to be absent, and sparteine, β-isosparteine, isolupanine, 5,6-dehydrolupanine, lupanine and anagyrine are the major alkaloids. The presence of the α-pyridone pathway is thus confirmed, with anagyrine as the major seed alkaloid in four of the five species. Lupinus seems to differ from other α-pyridone-bearing genera of the tribe Genisteae, which accumulate N-methylcytisine or cytisine in the seeds and not anagyrine. Despite the small number of samples and populations studied, the remarkable differences between the species showed that the alkaloids of Lupinus may provide valuable taxonomic information even at the species level.